27 - Amines, Amino Acids and Polymers

Question 1

What is Condensation Polymerisation?

Answer 1

Condensation polymerisation is the joining of monomers with a loss of a small molecule , usually water (condensation) or hydrogen chloride, and two different functional groups are needed.

Question 2

How is polyester formed?

Answer 2

Through ‘Esterification’, by the condensation reaction between a carboxylic acid group and an alcohol group forming water that is the small molecule that is eliminated.

Question 3

What are the three differences in Condensation polymerisation from addition Polymerisation?

Answer 3

• Two different functional group, either two different monomers or with the same monomer.
• A small molecule (normally water) is eliminated when the monomers join together.
• The main polymer chain contains atoms other that carbon (like oxygen, nitrogen)

Question 4

What do polyesters contain in there main polymer chain?

Answer 4

Carbon and Oxygen

Question 5

How are Polyamides through Condensation?

Answer 5

Polyamides are formed by the condensation reaction between a dicarboxylic acid and a diamine, forming water as the small molecule eliminated.

Question 6

What do polyamide contain in their main polymer chain?

Answer 6

Carbon and NITROGEN as the monomers are joined together by an amide group.

Question 7

What are the three characteristics of condensation polymerisation?

Answer 7

1. Two monomers, each with two functional groups.
2. One monomer with two different functional groups.
3. Polymer contains ester or amide linkages.

Question 8

What is the ester link in polyester?

Answer 8

-COO-

 O
|| — C — O—

Question 9

What is the amide links in polyamides?

Answer 9

-CONH-

          O
         || — N — C —
 |
 H

Question 10

How can condensation polymerisation be reversed?

Answer 10

Through hydrolysis, water molecules are added back in and the link are broken.

Remember - Water is removed when condensation polymers are formed.

Question 11

Why is water not used in practice for the hydrolysis of condensation polymerisation and what instead is used?

Answer 11

Water is far too slow, so the reaction is done with an acid or base.

Question 12

How do you hydrolyse a Polyamide and what’s the formula?

Answer 12

With an Acid called H+

Polyamide —> Dicarboxylic acid + diamine

Question 13

How do you hydrolyse a Polyester and what is formed what’s the formula?

Answer 13

Polyester will hydrolyse with a base and form a metal salt of carboxylic acid is formed.

Polyester —> Dicarboxylic Acid Salt + Diol

Question 14

How do you find the monomers of a condensation polymers?

Answer 14

1) Find the amide (HN-CO) or ester (CO-O) link and break the main chain polymer in half (N-C or C-O).

2) The add a H or and OH to both ends of both molecules to find the monomers.

Always add H’s to an O or N atoms.
Always add OH to C atoms.

Question 15

What is the key rule for when add OH or H to end of molecules when finding the monomers of a condensation polymer?

Answer 15

Always add H’s to an O or N atoms.
Always add OH to C atoms.

Question 16

How do you join two monomers (diamine and dicarboxylic acid) to form a polyamide?

Answer 16

1) Draw out the two monomers molecules next to each other.
2) Remove an OH from the dicarboxylic acid, and an H from diamine (this gives you a water molecule)
3) Join the C and N together to make an amide link.
4) Take another H and OH off the ends of your molecule, draw brackets around it and that’s the repeating unit.

Question 17

How do you join two monomers (diol and dicarboxylic acid) to form a polyester?

Answer 17

1) Draw out the two monomers molecules next to each other.
2) Remove an OH from the dicarboxylic acid, and an H from diol (this gives you a water molecule)
3) Join the C and O together to make an ester link.
4) Take another H and OH off the ends of your molecule, draw brackets around it and that’s the repeating unit.

Question 18

Why there is a 2n as the repeating unit for H2O in condensation polymerisation?

Answer 18

As two water molecules are formed from removing two H molecules and two OH molecules from the original monomers.